Fix msvc/ecpg_regression.proj for recent ECPG test additions.
Commit
3b7ab4380 added some tests that require ecpg to be given the
new "-C ORACLE" switch. Teach the MSVC build infrastructure about
that.
Michael Paquier
Discussion: https://postgr.es/m/8299.
1521154647@sss.pgh.pa.us